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Introduce logical decoding.

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This feature, building on previous commits, allows the write-ahead log
stream to be decoded into a series of logical changes; that is,
inserts, updates, and deletes and the transactions which contain them.
It is capable of handling decoding even across changes to the schema
of the effected tables.  The output format is controlled by a
so-called "output plugin"; an example is included.  To make use of
this in a real replication system, the output plugin will need to be
modified to produce output in the format appropriate to that system,
and to perform filtering.

Currently, information can be extracted from the logical decoding
system only via SQL; future commits will add the ability to stream
changes via walsender.

Andres Freund, with review and other contributions from many other
people, including Álvaro Herrera, Abhijit Menon-Sen, Peter Gheogegan,
Kevin Grittner, Robert Haas, Heikki Linnakangas, Fujii Masao, Abhijit
Menon-Sen, Michael Paquier, Simon Riggs, Craig Ringer, and Steve
Singer.
This commit is contained in:
Robert Haas
2014-03-03 16:32:18 -05:00
parent de94b47c0a
commit b89e151054
89 changed files with 12998 additions and 194 deletions
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14
src/include/access/heapam_xlog.h
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@ -48,7 +48,7 @@
* the ones above associated with RM_HEAP_ID. XLOG_HEAP_OPMASK applies to
* these, too.
*/
/* 0x00 is free, was XLOG_HEAP2_FREEZE */
#define XLOG_HEAP2_REWRITE 0x00
#define XLOG_HEAP2_CLEAN 0x10
#define XLOG_HEAP2_FREEZE_PAGE 0x20
#define XLOG_HEAP2_CLEANUP_INFO 0x30
@ -332,6 +332,17 @@ typedef struct xl_heap_new_cid
xl_heaptid target;
} xl_heap_new_cid;
/* logical rewrite xlog record header */
typedef struct xl_heap_rewrite_mapping
{
TransactionId mapped_xid; /* xid that might need to see the row */
Oid mapped_db; /* DbOid or InvalidOid for shared rels */
Oid mapped_rel; /* Oid of the mapped relation */
off_t offset; /* How far have we written so far */
uint32 num_mappings; /* Number of in-memory mappings */
XLogRecPtr start_lsn; /* Insert LSN at begin of rewrite */
} xl_heap_rewrite_mapping;
#define SizeOfHeapNewCid (offsetof(xl_heap_new_cid, target) + SizeOfHeapTid)
extern void HeapTupleHeaderAdvanceLatestRemovedXid(HeapTupleHeader tuple,
@ -341,6 +352,7 @@ extern void heap_redo(XLogRecPtr lsn, XLogRecord *rptr);
extern void heap_desc(StringInfo buf, uint8 xl_info, char *rec);
extern void heap2_redo(XLogRecPtr lsn, XLogRecord *rptr);
extern void heap2_desc(StringInfo buf, uint8 xl_info, char *rec);
extern void heap_xlog_logical_rewrite(XLogRecPtr lsn, XLogRecord *r);
extern XLogRecPtr log_heap_cleanup_info(RelFileNode rnode,
TransactionId latestRemovedXid);